This invention relates to medical grafting methods and apparatus, and more particularly to methods and apparatus for connecting or fastening tubular bypass grafts.
An example of the possible uses of the invention is a minimally invasive cardiac bypass procedure. This example will be considered in detail, but it will be understood that various aspects of the invention have many other possible uses.
Several procedures are known for revascularizing the human heart in order to treat a patient with one or more occluded coronary arteries. The earliest of these procedures to be developed involves exposing the heart by means of a midline sternotomy. Following surgical exposure of the heart, the patient""s aorta and vena cava are connected to a heart/lung machine to sustain vital functions during the procedure. The beating of the heart is stopped to facilitate performance of the procedure. Typically, a suitable blood vessel such as a length of the patient""s saphenous (leg) vein is harvested for use as a graft. The graft is used to create a new, uninterrupted channel between a blood source, such as the aorta, and the occluded coronary artery or arteries downstream from the arterial occlusion or occlusions. A variation of the above procedure involves relocating a mammary artery of the patient to a coronary artery.
Although the above-described sternotomy procedures are increasingly successful, the high degree of invasiveness of these procedures and the requirement of these procedures for general anesthesia are significant disadvantages. Indeed, these disadvantages preclude use of sternotomy procedures on many patients.
More recently, less invasive procedures have been developed for revascularizing the heart. An example of these procedures is known as thoracostomy, which involves surgical creation of ports in the patient""s chest to obtain access to the thoracic cavity. Specially designed instruments are inserted through the ports to allow the surgeon to revascularize the heart without the trauma of a midline sternotomy. Drugs may be administered to the patient to slow the heart during the procedure. Some thoracostomy procedures involve relocating a mammary artery to a coronary artery to provide a bypass around an occlusion in the coronary artery.
Thoracostomy bypass procedures are less traumatic than sternotomy bypass procedures, but they are still too traumatic for some patients. Also, the number of required bypasses may exceed the number of mammary arteries, thereby rendering thoracostomy procedures inadequate to fully treat many patients.
Another technique for revascularizing the human heart involves gaining access to the thoracic cavity by making incisions between the patient""s ribs. This procedure is known as thoracotomy. It is also substantially less traumatic than midline sternotomy, but it is still too traumatic for some patients.
In view of the foregoing, even less traumatic approaches have been developed for revascularizing a patient, as described in Goldsteen et al. U.S. Pat. No. 5,976,178, which is hereby incorporated by reference herein in its entirety. With such approaches, a graft (e.g., of saphenous vein) can be delivered to an operative site in the patient through the patient""s existing arteries and veins. The graft is typically inserted between two attachment sites in the patient""s existing body organs (e.g., between a site along the patient""s aorta and a site along the coronary artery downstream from a coronary artery occlusion).
Thus the above-mentioned Goldsteen et al. reference shows, among other things, methods and apparatus for installing tubular bypass grafts intralumenally. The Goldsteen et al. reference shows methods and apparatus in which each end of the graft site is approached separately and intralumenally, penetrated, and then a longitudinal structure (e.g., element 150 in the Goldsteen et al. reference) is established between the ends of the graft site. This longitudinal structure may extend intralumenally all the way out of the patient""s body from both ends of the graft site. The graft is fed into the patient""s body intralumenally along the longitudinal structure until it is in the desired position extending from one end of the graft site to the other. Each end of the graft is then secured at a respective end of the graft site and the longitudinal structure is withdrawn from the patient.
Tubular artificial grafts are needed in various medical procedures. For example, such grafts may be needed to replace diseased or damaged sections of natural tubular body tissue such as in the circulatory system, the urinary tract, etc. Or such grafts may be needed to make new connections in natural tubular body tissue systems such as bypass or shunt connections in the circulatory system. In general, an artificial tubular graft may be needed as either a temporary or permanent installation.
Important considerations regarding the use of artificial grafts include ease of use, time required for installation, secureness of installation, and performance after installation. Improvements are constantly sought in all of these areas.
It is therefore an object of this invention to provide improved grafts.
It is therefore a further object of this invention to provide improved methods and apparatus for the connection of grafts, whether natural or artificial.
It is therefore a further object of the invention to provide improved graft structures for use in the repair, replacement, or supplementing of natural body organ structures or tissues, and to provide methods and apparatus for fastening or connecting such graft structures.
It is therefore a further object of this invention to provide improved methods and apparatus for installing medical grafts, whether natural or artificial.
This and other objects of the invention are accomplished in accordance with the principles of the invention by providing apparatus for use as a body tissue graft and methods for securing the graft in a patient comprising a frame structure made of a first elastic material, a covering of a second elastic material on the frame structure, the covering substantially filling openings in the frame structure, and a connector connected to the frame structure. Projections are secured to the connector structure. The projections facilitate attachment of the tubular graft in a patient by securing the graft to the body tissue with which the graft is employed. The connector selectively circumferentially expands and the projections selectively circumferentially expand. This may be done using an inflatable balloon to circumferentially expand the projections and the connector. A restraining member may be provided to restrain the projections in a cone shape so that an end of the graft may be used to open an aperture through a side wall of existing body organ tubing and a portion of the projections may enter the aperture. The connector structures of this invention may be used with artificial grafts having any construction (i.e., other than the frame-and-covering construction mentioned above), and they may also be used with natural body tissue grafts.
Further features of the invention, its nature, and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments.